<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .toast-container{
            position: absolute;
            left: 0;
            right: 0;
            top: 0;
            bottom: 0;
            z-index: 2000;
            display: flex;
            /*水平居中*/
            justify-content: center;
            /*垂直居中*/
            align-items: center;
        }
        .toast{
            width: 180px;
            height: 60px;
            line-height: 60px;
            text-align: center;
            background: rgba(0,0,0,0.61);
            border-radius: 10px;
            color: white;
        }
    </style>
</head>
<body>

    <section class="toast-container">
        <div class="toast">
            <span>Hello, Toast</span>
        </div>
    </section>

</body>
</html>